Prior art anionic polymerization processes of conjugated dienes and monoalkenyl arenes are described in U.S. Pat. Nos. 4,039,593 and Re. 27,145, which are hereby incorporated herein by reference. Typical living anionic polymer structures formed using such prior processes include:
R--A--Li PA0 R--A/B--Li PA0 R--A--B--Li PA0 R--A/B--B--Li PA0 R--A--A/B--Li PA0 R--A--B--A--Li
wherein A and B each represent polymerized units of a single anionically-polymerizable monomer, A/B represents random polymerized units of two different anionically-polymerizable monomers, and R is the residue of the lithium initiator.
Use of initiators which include a protected functional group is also known in the art. After polymerization, the protective group can be removed to yield a polymer having a desired terminal functional group. For example, U.S. Pat. No. 5,331,058, incorporated herein by reference, teaches use of an alkyl lithium initiator having a terminal trimethylsilyl group. After the anionic polymerization is complete, the trimethylsilyl group can later be removed leaving a hydroxy-terminated hydrocarbon polymer.
This prior art technology, however, only allows incorporating functionally at the terminus of the polymer chain. Copolymerization of monomers having protected functional groups leads to a random distribution of such functionality throughout the polymers formed.
Applicant's novel process, however, allows more precise placement of protected functionality along the molecules structure of a hydrocarbon polymer. Therefore, the molecular weight between such functional groups can be better controlled to form more useful polymeric materials.